Rotary switch

ABSTRACT

A rotary switch comprising: a plurality of n different fixed contacts where n is an integer at least equal to 2, said contacts being disposed in spaced position along a circle and designated as the first, second. . . . and nth contacts respectively; an electrically conductive wiper extending radially outward from the center of the circle and fixed in position at the center, the opposite end of the wiper making electrical connection with any fixed contact when the wiper is properly positioned; first means responsive to incoming pulses to cause said wiper to rotate through a selected arc each time a pulse is received whereby said wiper can be successively advanced to make electrical connection with each of the first, second . . . and nth contacts in turn and thereafter to repeat the sequence as required, said wiper when connected to said first contact being in the home position; a pair of normally closed contacts; and second means responsive to the rotation of the wiper to separate the contact in said pair when and only when the wiper is in home position.

United States Patent 1191 Elliott [4 1March 13, 1973 1 ROTARY SWITCHKenneth F. Elliott, Bexley, Kent, England [75] Inventor:

[58] Field of Search ..335/1l4,118,l38,139,125, 335/73, 190; 290/38;318/466, 470

[56] References Cited UNITED STATES PATENTS 1,279,893 9/1918 McQuarrie..335/117 2,844,656 7/1958 Lohs ..335/l22 FOREIGN PATENTS ORAPPLICATIONS 658,244 3/1938 Germany ..335/l18 298,238 10/1927 Germany..335/l 18 Primary ExaminerHarold Broome Att0rney-Theodore C. Jay et al.

STEP

PULSES [57] ABSTRACT A rotary switch comprising: a plurality of ndifferent fixed contacts where n is an integer at least equal to 2, saidcontacts being disposed in spaced position along a circle and designatedas the first, second. and nth contacts respectively; an electricallyconductive wiper extending radially outward from the center of thecircle and fixed in position at the center, the opposite end of thewiper making electrical connection with any fixed contact when the wiperis properly positioned; first means responsive to incoming pulses tocause said wiper to rotate through a selected are each time a pulse isreceived whereby said wiper can be successively advanced to makeelectrical connection with each of the first, second and nth contacts inturn and thereafter to repeat the sequence as required, said wiper whenconnected to said first contact being in the home position; a pair ofnormally closed contacts; and second means responsive to the rotation ofthe wiper to separate the contact in said pair when and only when thewiper is in home position.

3 Claims, 14 Drawing Figures PATENTEU MAR 1 3 I975 SHEET 10F 3 INVENTOR.

KENNETH F ELuo'l PATENTEDMAR 13 I975 SHEET 20F 3 STEP PULSES INVENTOR.

PATENTEDMARIB I973 3.720.893 SHEET 3 UF 3 INVENTOR.

KENNETH F. ELLIOT Y w B My ROTARY SWITCH THE PRIOR ART British Pat. No.l,l47,690 discloses an electromechanical rotary switch having a contactwiper in the form of a single flexible member fixed at one end and madeto sweep in a rotary motion at the other. This wiper has a straightportion which rests normally on one of a number of contacts disposed inspaced positions along a circle centered on fixed point.

The switching motion is derived from two hollow cylinders disposedvertically and concentrically one within the other, each cylinder havinga circular profile of saw tooth form on its upper edge. The outercylinder is stationary and its profile does not move. The inner cylindercan be reciprocated back and forth along its axis whereby the innerprofile moves toward and away from the wiper. The inner and outerprofiles have teeth which are relatively displaced angularly byapproximately half a pitch. The motion of the inner cylinder towards thewiper lifts the straight portion of the wiper laying radially acrossboth profiles at a common point on their circumferences, over the tip ofthe tooth of the outer cylinder and so to slide down the face of theback of the tooth (which is sloping) to be brought to a halt by the nearvertical face of the next tooth of the inner cylinder. The innercylinder is then allowed to return to its former position, allowing thewiper to continue down the slope of the outer tooth and consequentlyover the tip of the inner tooth, the wiper coming to rest on the nextcontact face.

The wiper can thus be caused to step around the peripherally disposedfixed contacts in successive circles, each complete circle being acomplete cycle. However, if one specified contact is designated as thezero or homing contact, it will be seen thatthe wiper, once having leftthe zero or home position, can only be return thereto after completionof a switching cycle.

For many applications, as for example in telephony, it is necessary toprovide means in such a rotary switch which can override all otheroperations upon command and cause the wiper to be automatically returnedin one continuous movement to home position. This known switch lackssuch means.

SUMMARY OF THE INVENTION My invention is directed toward a rotary switchof the type described above which is provided with automatic homingcontrol. To this end, my rotary switch employs a plurality of ndifferent fixed contact where n is an integer at least equal to 2, saidcontacts being disposed in spaced position along a circle and designatedas the first, second and nth contacts respectively. The switch alsoincludes an elongated electrically conductive wiper extending radiallyoutward from the center of the circle. The inner end of the wiper isfixed. Its outer end makes electrical connection with any fixed contactwhen the wiper is properly positioned.

First means responsive to incoming pulses causes the wiper to rotatethrough a selected are each time a pulse is received whereby said wipercan be successively advanced to make electrical connection with each ofthe first, second and nth contacts in turn and thereafter to repeat thesequence as required. The position of the wiper when connected to saidfirst contact is designated in the home position.

In order to control the homing action, the switch is also provided witha pair of normally closed contacts. Second means responsive to therotation of the wiper cause the contacts in said pair to separate whenand only when the wiper is in home position. Third means when energizedthrough the closed contacts of the pair cause the wiper to beautomatically advanced in one continuous motion from any other positionto the home position. The third means is automatically disabled when thecontacts in said pair are separated.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings:

FIG. 1 shows, in side elevation, one embodiment of my invention;

FIG. 2 is a top view thereof;

FIG. 3 is a cross section taken along line 3 3 in FIG. 2;

FIG. 4 is a view taken along line 4 4 in FIG. 3;

FIGS 5-9 are diagramatic views illustrating various steps in theswitching operation employed in my switch;

FIG. 10 is a view taken along line 10 10 in FIG. 3;

FIG. 11 is a view similar to FIG. 10 but showing the contacts indifferent positions;

FIG. 12 is aside view of a modification of the contacts arrangementshown in the preceding Figures;

FIG. 13 is a view similar to FIG. 12 but showing another modification;and

FIG. 14 is a view taken along line 14 14 in FIG. 13.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS Referring first to FIGS 111, my switch comprises a vertical cylindrical housing 10 closed at itsends by top plate 12 and base plate 14 which serve as caps. The casing10 is provided with an inner annular shoulder 20 against which is seateda radial flange 22 of a hollow cylindrical insulating vertical member 4.Member 4 has a top horizontal edge with stationary saw teeth 24. Asecond hollow cylindrical insulated member 6 constrained to movevertically up and down is disposed concentrically within number 4.Member 6 has a top horizontal edge with saw teeth 26. The teeth in thetwo members 4 and 6 are offset by approximately half a pitch.

A plurality of electrical contacts 2 are disposed horizontally andextend inward through the housing to lie in equidistantly spacedpositions along a circle centered around the axis of the housing.

An elongated electrically conductive wiper has a wiper portion 8 whichoverlies anyone of contacts 2 and is in electrical engagement therewith.Wiper portion 8 is at the end of an arm 16 which extends horizontallyfrom a helical spring section 18 across the two saw teeth portions ofmembers 4 and 6.

Section 18 extends inclinedly downward from an opening 28 in the centerof plate 12. An electrically non-conductive support serves as a core 30about which the spring is disposed. A vertical top portion 32 of thesupport carries a vertical cam surface 34. A pair of normally closedcontacts 36 and 38 cooperate with the cam surface in a manner describedbelow.

Member 6 is secured at its center to the top end of a non-magnetic bar40 vertically disposed and aligned with the axis of the housing. Thebottom end of the bar is secured via bias spring 42 to the center ofbottom plate 3 and is also secured to a magnetic piston 84. Guide means44 restrains the bar so that it cannot move horizontally.

A relay type coil 46 has a vertical central bore in which the bar 40 isdisposed.

When the coil is energized by a pulse applied between the two endterminals, member 6 is raised and its saw teeth extend above the levelof the saw teeth of member 4. As soon as the coil is deenergized, spring42 will pull member 6 downward until its teeth are below the level ofthe teeth of member 4. This motion, because of the relative offset ofthe teeth of the two members, causes the arm 16 to describe and arc andwiper 8 to advance from engagement with one contact 2 to engagement withthe next adjacent contact 2 each time coil 46 is pulsed by individualstep pulses.

In order to perform the homing action, contacts 36 are connected incircuit with an on-off switch 50 and a generator 52 of a pulse train.This generator is also coupled to the coil 46. When switch 50 is open nohoming action occurs. When switch 50 is closed, coil 46 is periodicallyand rapidly pulsed and the arm is stepped around until the arm reaches aposition at which the wiper engages a selected one of contacts 2designated as a home contact and identifying home position. At thispoint contacts 36 and 38 separate breaking the circuit.

Contacts 36 and 38 cooperate with the cam surface 34. As the arm 16moves, this surface rotates. The surface is so arranged that thecontacts 36 and 38 separate only at the home position as shown in FIGS.and 11.

In FIG. 12, blade contacts 60 and 62 are substituted for contacts 36 and38. The function remains the same.

In FIGS.'l3 and 14, commutator contacts 70 and 72 are substituted forcontacts 36 and 38, and the cam surface is modified as shown at 74. Thefunction still remains thesame.

While I have described my invention with particular reference to thedetailed embodiments, my protection is to be limited only by the termsof the claims which follow.

Iclaim:

l. A rotary switch comprising a first cylindrical member havingstationary saw teeth on one edge thereof;

a second cylindrical member including stationary saw teeth on one edgethereof and being slideably mounted in a longitudinal directionconcentrically within said first cylindrical member, the saw-tooth edgeof said second cylindrical member being positioned lower than and offsetfrom the saw-tooth edge of said first cylindrical member;

means responsive to a first signal source for causing longitudinalmovement of the cylindrical members with respect to each other;

a plurality of n different contacts where n is an integer of at leasttwo, said contacts being disposed concentric with one of saidcylindrical members;

wiper means including a caming surface on one end thereof and beingresponsive to the axial movement of said second cylindrical member toadvance the other end along said plurality of contacts; and homingmeans, mechanically coupled to said caming surface and electricallycoupled to means for causing longitudinal movement being operative inresponse to a second signal source to return said wiper means to apredetermined one of said plurality of n contacts from any other one ofsaid plurality of n contacts.

2. A rotary switch according to claim 1 wherein said wiper meansincludes a coil spring having one end substantially orthogonal to theconcentric axis of said first and second cylindrical members and theother end substantially parallel thereto; and

a core member fixedly positioned within said coil spring and rotatablymounted with respect to the axis of said first and second cylindricalmembers, said core member having a concentrically increasing camingsurface and having a transition between the high and low portionsassociated with the predetermined one of said plurality of n contacts.

3. A rotary switch according to claim 2 wherein said homing meansincludes switching means including a pair of normally closed contacts,one contact of said pair being tangentially displaced along said camingsurface from the other contact of said pair such that said one contactpasses over the transition and drops to the lower portion of said camingsurface to thereby open the normally closed contacts; and

connecting means coupled between the second source of signals and saidmeans for causing and being adaptive to couple signals from said secondsource to said means for causing when said pair of contacts are in thenormally closed condition.

1. A rotary switch comprising a first cylindrical member havingstationary saw teeth on one edge thereof; a second cylindrical memberincluding stationary saw teeth on one edge thereof and being slideablymounted in a longitudinal direction concentrically within said firstcylindrical member, the saw-tooth edge of said second cylindrical memberbeing positioned lower than and offset from the saw-tooth edge of saidfirst cylindrical member; means responsive to a first signal source forcausing longitudinal movement of the cylindrical members with respect toeach other; a plurality of n different contacts where n is an integer ofat least two, said contacts being disposed concentric with one of saidcylindrical members; wiper means including a caming surface on one endthereof and being responsive to the axial movement of said secondcylindrical member to advance the other end along said plurality ofcontacts; and homing means, mechanically coupled to said caming surfaceand electrically coupled to means for causing longitudinal movementbeing operative in response to a second signal source to return saidwiper means to a predetermined one of said plurality of n contacts fromany other one of said plurality of n contacts.
 1. A rotary switchcomprising a first cylindrical member having stationary saw teeth on oneedge thereof; a second cylindrical member including stationary saw teethon one edge thereof and being slideably mounted in a longitudinaldirection concentrically within said first cylindrical member, thesaw-tooth edge of said second cylindrical member being positioned lowerthan and offset from the saw-tooth edge of said first cylindricalmember; means responsive to a first signal source for causinglongitudinal movement of the cylindrical members with respect to eachother; a plurality of n different contacts where n is an integer of atleast two, said contacts being disposed concentric with one of saidcylindrical members; wiper means including a caming surface on one endthereof and being responsive to the axial movement of said secondcylindrical member to advance the other end along said plurality ofcontacts; and homing means, mechanically coupled to said caming surfaceand electrically coupled to means for causing longitudinal movementbeing operative in response to a second signal source to return saidwiper means to a predetermined one of said plurality of n contacts fromany other one of said plurality of n contacts.
 2. A rotary switchaccording to claim 1 wherein said wiper means includes a coil springhaving one end substantially orthogonal to the concentric axis of saidfirst and second cylindrical members and the other end substantiallyparallel thereto; and a core member fixedly positioned within said coilspring and rotatably mounted with respect to the axis of said first andsecond cylindrical members, said core member having a concentricallyincreasing caming surface and having a transition between the high andlow portions associated with the predetermined one of said plurality ofn contacTs.